The present invention relates to a method for conducting a vapor-liquid contact reaction semi-batchwise wherein a reaction product of good quality is obtained while preventing increase in pressure of the reactor and also to an apparatus for conducting a vapor-liquid contact reaction semi-batchwise.
In the prior art vapor-liquid contact reaction, a gaseous starting material or a liquid starting material capable of being converted into vapor on reaction often forms an azeotrope with the reaction product or a by-product. If the boiling point of such starting material is close to that of the reaction product or by-product, it is difficult in the aspects of facilities and economy to perform the reaction in a process wherein the reaction product or by-product is separated continuously from the reaction system while the gaseous starting material or the liquid starting material capable of being converted into vapor is recovered and used again. For these reasons, the apparatus is modified to a confined system conducted semi-batchwise and the process is carried out in such manner that the reaction product or by-product is taken out or separated after all or almost all of the gaseous starting material or the liquid starting material capable of being converted into vapor on reaction is consumed. However, this process adopting such confined reaction system requires the use of a reactor tolerant to high pressure and thus has the following drawbacks:
1. The reactor has to be equipped in total with high safeguard facilities.
2. The expense for the facilities is considerable.
As a result of many researches made for overcoming the above drawbacks, it has now been found that the drawbacks in the prior art processes can be overcome by drawing a part of the reaction liquid from the reactor, bringing the drawn liquid into contact and reaction with a gaseous starting material or a liquid reaction material capable of being converted into vapor on reaction by means of pipe-line mixing and recycling this reaction liquid to the reactor. The present invention has been accomplished on the basis of the above finding.